Roberto's alleged killers, who had mistaken him for a rival gang member, were eventually arrested thanks to police surveillance cameras that captured the getaway. They are among 2,000 law enforcement cameras, mounted on poles and buildings across the city, that offer authorities a bird's-eye view of drug deals, violent and property crime and potential terrorism.

"We see a reduction in crime in the areas around the cameras," said Chicago Police Commander Jonathan Lewin. "The last three years are the first three-year period in over 40 years that we've had less than 500 homicides a year, and we think the cameras played a role in that."

Watch Eric Horng's story on the debate over surveillance cameras tonight on "World News." Check local listings for air time.

The roving electronic eyes, which Chicago began installing four years ago and are now going up at the rate of 15 per week, are powerful enough to read vehicle license plates and even the ticket prices listed on a sign outside the Chicago Cubs' Wrigley Field box office.

And they listen as well as look. Some of the cameras, which cost up to $30,000 apiece, are equipped with gunshot detectors that can alert police when bullets start flying. Eventually, they may even be able to sniff out biological or chemical agents in the event of a terrorist attack.

"I think it contributes to people's sense of well-being," said Lewin of the highly-visible cameras, many of which have blue flashing lights. "We can record video from the cameras and if something happens, we can go back and use the video as evidence in court."

While Chicago's network of cameras has received accolades from law enforcement agencies coast-to-coast, the gold standard in surveillance systems belongs to London.

Originally devised three decades ago to guard against attacks by the Irish Republican Army, London's four-million cameras and sensors helped detectives quickly identify suspects in last June's failed car bombings as well as the July 2005 train and bus attacks that killed more than 50 people.

"The Brits have got something smart going in England," Sen. Joseph Lieberman, I-Conn., who chairs the Senate Homeland Security and Governmental Affairs Committee, told ABC News earlier this summer. "I think it's just common sense to do that [in the U.S.] much more widely."

Several U.S. cities are doing just that. New York plans to blanket Manhattan with 3,000 cameras by 2010. Baltimore is expanding its current network of 500 cameras as well. And Miami, Los Angeles, and Chicago are looking to fold private sector cameras into their systems.

"It may not be feasible to put a police officer on every corner, but some day it might be possible to put a camera on every corner," said Lewin.

But critics worry more surveillance will mean less privacy for Americans.

"Will we become a society where every single move you make outside, maybe even inside your home, is being watched?" said Melissa Ngo, senior counsel at the Electronic Privacy Information Center.

She pointed to what she felt have been some alarming examples of misuse: At the 2004 Republican National Convention in New York, a police helicopter's night vision camera that was trained on protestors also recorded a couple's intimate rendezvous on a terrace. That same year, a San Francisco cop used airport cameras to ogle female air travelers. And in 2006, New York's police union sued the city for what it considered excessive monitoring during a contract dispute.

"There needs to be strict regulations in place in order to curb such abuses, and there also needs to be a culture where such abuses will not be acceptable," said Ngo.

Some also question whether the cameras deter terrorists.

"For the jihadist who is not concerned about being caught and is willing to kill themself during the execution of a bombing or any other terrorist type event, cameras are more of a forensic tool then they are a deterrent," said Jerry Hauer, former director of New York City's Office of Emergency Management and an ABC News consultant.

"I would much rather see devices that can detect explosives at a distance and sound an alarm the moment a threat vehicle gets near high risk," said Hauer. "Detection and intervention is better than remote observation by camera. I think we are putting too much money into band-aids like this and not real solutions for preventing an incident."

Cameras did not prevent Roberto Duran's death, but with his alleged killers now behind bars, these eyes in the sky have given his family some measure of solace.

"They are wrong," Roberto's father said of those who oppose the use of surveillance. "Cameras helped a lot in this case."